1. Field of the Invention
The present invention relates generally to an IC testing method and apparatus and, more particularly, to an IC testing method and apparatus according to which a handler in a loader arm operating stage carries only yet-to-be untested devices (hereinafter referred to as untested devices) and a handler in an unloader arm operating stage carries only tested devices.
2. Description of the Related Art
A prior art example will hereinbelow be described with reference to FIGS. 1 and 2. FIGS. 1 and 2 are conceptual diagrams for explaining the path over which untested devices 19 are brought from a loader arm operating stage ST1 to an unloader arm operating stage ST2 through a loader buffer operating stage ST4, a contact arm operating stage ST3 and an unloader buffer operating stage ST5. FIG. 1 is a plan view and FIG. 2 a side view.
In FIGS. 1 and 2 the untested devices 19 are housed in a tray 11. A loader arm 10 placed in the loader arm operating stage ST1 has pick-and-place equipment 13 at its lower end. Reference numeral 1Z denotes a Z-direction loader carrier rail that is driven vertically. The pick-and-place equipment 13 is secured to the Z-direction loader carrier rail 1Z through the loader arm 10, and hence it is also driven vertically. Reference numeral 1Y denotes a Y-direction loader carrier rail that is driven longitudinally. The Z-direction loader carrier rail 1Z is mounted slidably on the Y-direction loader carrier rail 1Y, and hence it is also driven longitudinally. Reference numeral 1X denotes an X-direction loader carrier rail that is driven transversely. The Y-direction loader carrier rail 1Y is mounted on the X-direction carrier 1x, and hence it is driven transversely. The X-, Y- and Z-direction loader carrier rails 1X, 1Y and 1Z constitute a handler of the loader arm operating stage ST1.
An unloader arm 20 placed in the unloader arm operating stage ST2 has pick-and-place equipment 23 at its lower end. Reference numeral 2Z denotes a Z-direction unloader carrier rail that is driven vertically. The pick-and-place equipment 23 is mounted slidably on the Z-direction unloader carrier rail 2Z through the unloader arm 20, and hence it is also driven vertically. Reference numeral 2Y denotes a Y-direction unloader carrier rail that is driven longitudinally. The Z-direction unloader carrier rail 2Z is mounted slidably on the Y-direction unloader carrier rail 2Y, and hence it is also driven longitudinally. Reference numeral 2X denotes an X-direction unloader carrier rail that is driven transversely. The Y-direction unloader carrier rail 2Y is mounted slidably on the X-direction unloader carrier rail 2X, and hence it is driven transversely. The X-, Y- and Z-direction unloader carrier rails 2X, 2Y and 2Z constitute a handler of the unloader arm operating stage ST2. Tested devices 29 are housed in a tested device housing tray 21.
A contact arm 30 placed in the contact arm operating stage ST3 has at its lower end a contact head H. Reference numeral 3Z denotes a Z-direction head carrier rail that is driven vertically. The contact head H is secured to the Z-direction head carrier rail 3Z through the contact arm 30, and hence it is also driven vertically. Reference numeral 3Y denotes a Y-direction head carrier rail that is driven longitudinally. The Z-direction head carrier rail 3Z is mounted slidably on the Y-direction head carrier rail 3Y, and hence it is also driven longitudinally. Reference numeral 3X denotes an X-direction head carrier rail that is driven transversely. The Y-direction head carrier rail 3Y is mounted slidably on the X-direction head carrier rail 3X, and hence it is driven transversely.
The loader buffer operating stage ST4 spans the contact arm operating stage ST3 and the loader arm operating stage ST1. Reference numeral 4Y denotes a Y-direction loader buffer carrier rail, on which a loader buffer carrier 41 to be loaded with the untested device 19 is mounted and driven longitudinally.
The unloader buffer operating stage ST5 spans the contact arm operating stage ST3 and the unloader arm operating stage ST2. Reference numeral 5Y denotes a Y-direction unloader buffer carrier rail, on which an unloader buffer carrier 51 to be loaded with the tested device 29 is mounted and driven longitudinally.
IC devices are each brought from the stage ST1 to ST2 through operations 1 to 9 that are carried out in this order as described below.
1 To begin with, the X- and Y-direction loader carrier rails 1X and 1Y are driven to bring the loader arm 10 to the position 1 just above the untested device housing tray 11.
2 The Z-direction loader carrier rail 1Z is driven to bring the pick and place equipment 13 down to the untested device 19 to pick it up by suction.
3 The X-, Y- and Z-direction loader carrier rails 1X, 1Y and 1Z are driven to bring the loader arm 10 to the position just above the loader buffer 41 while holding the untested device by the pick-and- place equipment 13. Then the pick-and-place equipment 13 is deactivated to unload therefrom the untested device 19 onto the loader buffer carrier 41. Following this, the Y-direction loader buffer carrier rail 4Y is driven to convey the loader buffer 41 loaded with the untested device 19 from the loader arm operating stage ST1 to the contact arm operating stage ST3.
4 In the contact arm operating stage ST3, the X-, Y and Z-direction head carrier rails 3X, 3Y and 3z are driven to bring the contact arm 30 to the position of the conveyed loader buffer carrier 41. Then the contact head H is activated to pick up the untested device 19 from the loader buffer carrier 41 by suction.
5 The X-, Y- and Z-direction head carrier rails 3X, 3Y and 3Z are driven to bring the contact arm 30 to the position just above a device testing part E while holding the untested device 19 by the contact head H. Then the contact head H is deactivated to place the untested device 19 at a predetermined position in the device testing part E for testing.
6 The X-, Y- and Z-direction head carrier rails 3X, 3Y and 3Z are driven to bring the contact arm 30 to the testing part E. Then the contact head H is activated to pick up the tested device 29 from the testing part E by suction.
7 The X-, Y- and Z-direction head carrier rails 3X, 3Y and 3Z are driven to bring the contact arm 30 to the position just above the unloader buffer 51 in the unloader buffer operating stage ST5 while holding the tested device 29 by the contact head H. Then the contact head H is deactivated to unload therefrom the tested device 29 onto the unloader buffer carrier 51. After this, the unloader buffer carrier 51 loaded with the tested device 29 is brought down by the Y-direction unloader buffer carrier rail 5Y to the unloader arm operating stage ST2.
8 The X-, Y- and Z-direction unloader carrier rails 2X, 2Y and 2Z are driven to bring the unloader arm 20 to the position just above the unloader buffer carrier 51. Then the pick-and-place equipment 23 is activated to pick up the tested device 29 from the unloader buffer carrier 51 by suction.
9 The X-, Y- and Z-direction unloader carrier rails 2X, 2Y and 2Z are driven to bring the unloader arm 20 to the position 9 in a tray 21 for receiving tested devices while sorting them. Then the pick- and-place equipment 23 is deactivated to unload therefrom onto the tested device housing tray 21.
In the above prior art example, since only one contact arm 30 is used to convey the untested devices 19 to the device testing part E and convey therefrom the tested devices 29, there is no possibility of mechanical components colliding or interfering with each other during the device transfer. It is needless to say, however, that the transfer by only one contact arm 30 is less efficient than in the case of using two contact arms as described below.
Referring next to FIG. 3, a second prior art example will be described which employs two contact arms. In contrast to the example shown in FIGS. 1 and 2, the contact arm operating stage ST3 is formed by two contact arm operating stages ST3.sub.1 and ST3.sub.2. Each contact arm operating stage ST3 has X-, Y- and Z-direction head carrier rails 3X, 3Y and 3z for moving the contact arm 30. The contact arm operating stages ST3.sub.1 and ST3.sub.2 share the loader buffer operating stage ST4 joining the loader arm operating stage ST1 to the contact arm operating stage ST3 and the unloader buffer operating stage ST5 joining the contact arm operating stage ST3 to the unloader arm operating stage ST2. Hence, the both contact arm operating stages ST3.sub.1 and ST3.sub.2 form a contact arm operation interfering stage ST3.sub.12 where they overlap.
The second prior art example uses two contact arms 30.sub.1 and 30.sub.2 to transfer the untested and tested devices 19 and 29. By appropriate control of the both contact arms 30.sub.1 and 30.sub.2, the transfer efficiency could be increased as compared with that in the case of using one contact arm. It is necessary, however, that a drive control unit including an electrical circuit for controlling the operation of the contact arms 30.sub.1 and 30.sub.2 be finished perfect; otherwise, the contact arms 30.sub.1 and 30.sub.2 are likely to interfere or collide with each other in the contact arm operation interfering stage ST3.sub.12.
FIG. 4 depicts a third prior art example, which uses two contact arms 30.sub.1 and 30.sub.2 mounted on and driven by a common X-direction head carrier rail 3X. In this instance, since loader and unloader buffer units 400 and 500 both handle both untested and tested devices 19 and 29, it is occasionally impossible to judge from their appearance whether the devices being transferred are untested or tested devices while the testing system is at a standstill due to an error in the handler or handlers or by some other reason.